To support container scenario, 2 HardLimit configs are added - (#22180)

To support container scenario, 2 HardLimit configs are added - (#22180)

GCHeapHardLimit - specifies a hard limit for the GC heap
GCHeapHardLimitPercent - specifies a percentage of the physical memory this process is allowed to use

If both are specified, GCHeapHardLimit is checked first and only when it's not specified
would we check GCHeapHardLimitPercent.

If neither is specified but the process is running inside a container with a memory
limit specified, we will take this as the hard limit:

max (20mb, 75% of the memory limit on the container)

If one of the HardLimit configs is specified, and the process is running inside a container
with a memory limit, the GC heap usage will not exceed the HardLimit but the total memory
is still the memory limit on the container so when we calculate the memory load it's based
off the container memory limit.

An example,

process is running inside a container with 200mb limit
user also specified GCHeapHardLimit as 100mb.

if 50mb out of the 100mb is used for GC, and 100mb is used for other things, the memory load
is (50 + 100)/200 = 75%.

Some notes on these configs -

+ The limit is the commit size.

+ This is only supported on 64-bit.

+ For Server GC the minimum *reserved* segment size is 16mb per heap, this is to avoid the
scenario where the hard limit is small but the process can use many procs and we end up
with tiny segments which doesn't make sense. We then keep track of the committed on the segments
so the total does not exceed the hard limit.